Cellulosic fibres formed by spinning a solution or dope are well known. Cellulosic fibres of the viscose type have been manufactured for many years by dissolving sodium cellulose xanthate in caustic soda to form a syrup-like spinning solution known as viscose and commonly referred to as a spinning dope. The spinning dope is spun by extruding it through fine holes into a coagulating bath of sulphuric acid and salts which neutralise the alkaline content of the viscose dope and regenerate the original cellulose as continuous filaments. If the orifice through which the viscose dope is extruded is an elongate slit it is possible to manufacture a thin sheet of cellulose. If the orifice is annular it is possible to manufacture a tube of cellulose.
Such cellulosic regenerated elongate members are extremely well known.
In more recent years it has been proposed to manufacture cellulosic regenerated elongate material by forming a true solution of cellulose in a solvent such as a tertiary amine N-oxide. The tertiary amine N-oxide cellulose solution is then extruded into a water bath to dissolve out the amine oxide and to re-form the cellulose in a continuous filament or strip or tube depending on the shape of the orifice through which the material has been extruded.